The aging mouse displays the same symptoms as those most often found in the aging human with presbycusis: perceptive hearing loss which is most extreme for high frequencies, with associated damage to the basilar portion of the organ of Corti. We have obtained volume-conducted auditory evoked potentials from auditory structures at the levels of the inner ear to the midbrain which support and expand upon these behavioral and anatomical age-dependent auditory losses. We will trace the development of these threshold and suprathreshold electrophysiological events and correlate them with behavioral auditory thresholds, suprathreshold behavior, and histological examination of the inner ear and brainstem. Interaction of genotype with environmental factors (noise, ototoxic drugs) will be examined. Since these electrophysiological techniques can be nontraumatically used on humans (under the rubrics of Electrochchleography and Far Field Auditory Brainstem Potentials), the longitudinal mouse studies may be directly compared to the human condition, and screening procedures may be developed for agents and techniques which can prevent presbycusis in man.